Process and device for cleaving laminated materials

ABSTRACT

Slates are split from a plate by uniformly gripping, as by suction, the opposite sides of the plate and then moving the gripping elements apart along a common axis at right angles to a plane of cleavage determined by a trigger cut made in an edge of the plate thereby to break the internal cohesive forces of the plane along said plane.

United States Patent [72] Inventor Bernard Viemon [56] References Cited 47 Place A. Gentric, 49 Trelaze, France UNITED STATES PATENTS H 2 32 1,228,690 6 1917 Monnet 51/235ux 5: e d 2 1971 1,771,943 7/1930 Tinnerholm." 125/24 l 1 l 1967 2,850,279 9/1958 Stoothoffi... 269/21UX 3; F 2,940,720 6 1960 Birb 269/21x am 568 2,976,037 3/1961 Steel 269/21UX FOREIGN PATENTS 4,980 2/1910 Great Britain 125/24 225,569 9/1909 Germany..... 125/24 Primary Examiner-Harold D. Whitehead Attorney-Spencer & Kaye [54] PROCESS AND DEVICE FOR CLEAVING g ABSTRACT: Slates are split from a plate by uniformly wing gripping, as by suction, the opposite sides of the plate and then [52] U.S.Cl 125/24 moving the gripping elements apart along a common axis at [51 Int. Cl B28d l/32 right angles to a plane of cleavage determined by a trigger cut [50] Field of Search 125/24; made in an edge of the plate thereby to break the internal 29/239; 51/235; 269/21 cohesive forces of the plane along said plane.

PROCESS AND DEVICE FOR CLEAVING LAMINATED MATERIALS BACKGROUND OF THE INVENTION I. Field of the Invention The invention relates to a process of and a device for cleaving laminated materials such as slates.

2. Description of the Prior Art In order to perform the splitting of a plate of laminated material, of slate for example, a knife or analogous tool is normally inserted into the edge of the plate along a chosen cleavage plane, and by controlled penetration of this tool, the plate is separated into two parts along the said cleavage plane. This is the method employed to produce slates or tiles for roofs, it is relatively chancy to perform and causes considerable wastage by breakage of the sheets or plates obtained by cleavage, if these latter are of little thickness.

It is an object of the present invention to provide a cleavage process and a device therefor which may be applied reliably and easily and which reduces the risk of accidental breakage of the sheets being formed by splitting.

SUMMARY According to one aspect the invention consists of a process for cleaving laminated materials, for example slates, which comprises breaking the internal cohesive forces of a plate of said material along a predetermined plane of cleavage by applying to each of the opposite surfaces of the plate the action of a uniform field of elementary forces possessing a resultant substantially at right angles to and directed away from the plane of cleavage.

According to another aspect, the invention provides a device for cleaving laminated materials, for example slates, comprising a base to support in a vertical position a plate of said material to be split into sheets along a predetermined plane of cleavage, gripper elements supported for movement towards and away from each other along a common axis at right angles to the plane of cleavage, and actuating means operable to effect said movements of the gripper elements whereby on engagement of the gripper elements with the opposite surfaces of the plate and movement thereof away from each other the gripper elements each apply to one of said surfaces a uniform field of elementary forces possessing a resultant along said axis in a direction away from said plane thereby to break the internal cohesive forces of the plate along said plane.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic perspective view of a plate of laminated material trimmed to correspond to a reference trihedron;

FIG. 2 is an end view of the plate of FIG. 1;

FIG. 3 shows the cleavage line of the plate of FIG. 2;

FIG. 4 is an elevation of a device according to the invention for splitting plates; and a FIG. 5 to 7 illustrate the mode of operation of the device of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG. I; shows a plate P of laminated material related to a reference trihedron O-X-Y-Z in which the plane X-O-Y is parallel to the cleavage planes of the material, the axis O-Z being at right angles to these planes, and in particular to the two outer surfaces 51 and S2 of the plate.

In order to perform the process according to the invention, a uniform field of elementary forces, Afl or A12, FIG. 2, producing resultants RI and R2 parallel to 0-2 and in the same direction as 0-Z for the surface S2 and in the opposite direction for the surface S], is applied to one of the two opposed surfaces S1, S2.

The amplitude of these resultants is chosen in such manner as to counteract and cancel the cohesive forces holding the sheets of material joined to each other, partially in the chosen cleavage plane.

As will be seen hereinafter, in practice, recourse is had to negative pressure, to establish uniform distribution of the elementary forces.

To assist cleavage, a splitting trigger" A, FIGS. 1 to 3, is preferably made in the section of the material, in the chosen cleavage plane.

In the case of slate, in particular, it has been observed that the process according to the invention offers the feature of ensuring equidimensional surfaces at the break A, even if the latter has been made in approximate manner relative to the plane equidistant from the surfaces S1 and S2, FIG. 3.

The break may be assisted by the application of external twisting forces T1, T2 on the faces S1, S2, FIG. 2, this twist being exerted simultaneously with the application of the forces Afl and Af2.

FIG. 4 illustrates a device for carrying the process into effect.

This device comprises a metal frame 10, comprising a base 12 arranged to support a plate P which is to be split, the plate P being disposed to be vertical on the base 12. At each side of the position occupied by the plate P are situated two gripper elements, in this case being two suction cups 14, each jointedly secured to the extremity of the rod 15 of a ram whose barrel [6 is secured to the frame 10. The rods 15 are axially aligned one with the other at right angles to the plane of the plate P. By actuation of the rams, the two suction cups 14 are moved towards and away from each other.

Each suction cup 14, FIG. 5, consists of a plate 18 whose outline substantially matches that of a plate P which is to be split, and which possesses a peripheral flange 19 in which is located a sealing joint or packing 20 made of flexible material. The axial length of the packing 20 is greater than that of the flange. The flange and joint of each suction cup face towards the plate P. The plate 18 comprises an opening surrounded by an end piece which is connected by a flexible pipe 22 to a source of negative pressure, not shown.

When a plate P is in position on the base 12, the two suction cups 14 are brought into contact with the surfaces 81 and 82 by action of the rams, after which a negative pressure is engendered in each of the cavities defined between the cups l4 and the corresponding surface of the plate P. The joints 20 are then compressed and ensure sealing between the suction cups and the plate P, FIG. 6.

The suction cups 14 are then moved away from each other by retraction of the reams to cause the cleaving action, FIG. 7. If desired, during the movement of the cups 14 away from each other the cups may be rotated relative one to the other, by means not shown, about their axes as to twist the surfaces of the plate to facilitate the splitting thereof.

To assist the splitting, as has already been stated, at least one cleavage trigger cut is made in an edge of the plate P. This trigger or triggers may conveniently be made by one or more blades 30 guided for vertical sliding movement in the frame 10 in the plane of cleavage, the blades 30 including a head 31 aligned with a striking element 32 operable in any desired manner, not shown.

It will be noted that during a splitting action, the sheets L1, L2, FIG. 7, become curved, one of their surfaces bearing the negative pressure of the suction cup and the other atmospheric pressure. To prevent an excessive defamation which could cause a breakage, the face of each of the plates I8 carries one or more abutments 33, FIG. 7.

If suffices to reconnect 'the pipes 22 to atmospheric pressure in order to secure release of the separated sheets.

The separation of the suction cups during a cleaving action occurs along the common axis of the rods 15 and this may suffice to effect cleaving. If desired, however, in order to assist cleavage there may, as stated above, be relative rotation of the suction cups around this axis, or, alternatively the suction cups may be tilted in a direction at an angle to this axis.

lclaim: l. A process for cleaving a slab of rigid laminated material along a cleaving plane of the slab, comprising the steps of:

applying to each of the opposed faces of the slab parallel to the cleavage plane a force which is uniformly distributed across a major portion of the face and which is directed away from the cleavage plane, the resultant of each force being substantially perpendicular to the cleavage plane and the total amplitude of the forces applied to the opposed faces being greater than the internal cohesive forces existing in the slab along the cleavage plane; and

maintaining the slab substantially planar as the applied forces overcome the internal cohesive forces along the cleavage plane.

2. A process according to claim 1 comprising the step of making a trigger cut in an edge of the slab near the cleavage plane.

3. A process as defined in claim 1 wherein said step of applying a force is carried out by applying a vacuum to each opposed face.

4. A device for cleaving a slab of rigid laminated material along a cleavage plane of the slab, comprising, in combinatron:

means for supporting the slab in a predetermined orientation;

two gripping means each engageable with a major portion of a respective one of the two opposed slab faces parallel to the cleavage plane; and

said gripping means being movable away from one another along a common axis perpendicular to the cleavage plane for maintaining the slab in its predetermined orientation while applying uniformly distributed forces to such major portions of the opposed slab faces, which forces are of sufficient amplitude to overcome the internal cohesive forces in the slab along the cleavage plane.

5. A device as defined in claim 4 further comprising: for each said gripping means;

a ram having a barrel secured to said means for supporting and a rod movable relative to said barrel; and

connecting means hingedly connecting said gripping means to said rod.

6. A device according to claim 3 wherein each said gripping means comprises a suction cup connected to a source of vacuum.

7. A device according to claim 6 wherein each suction cup comprises a plate provided with a peripheral flange housing a flexible sealing joint, and wherein the periphery of the plate substantially corresponds to that of the faces of the slab to be cleaved.

8. A device according to claim 7 wherein the plate of the cup is provided with abutments arranged to limit the movement of each face of the slab when the vacuum is applied between the suction cup and the slab.

9. A device according 'to claim 8 further comprising a sliding cutter operable to form a trigger cut in an edge of the slab to be cleaved.

10. A process as defined in claim 1 comprising the further step of additionally applying torsional forces to the opposed faces of the slab. 

1. A process for cleaving a slab of rigid laminated material along a cleaving plane of the slab, comprising the steps of: applying to each of the opposed faces of the slab parallel to the cleavage plane a force which is uniformly distributed across a major portion of the face and which is directed away from the cleavage plane, the resultant of each force being substantially perpendicular to the cleavage plane and the total amplitude of the forces applied to the opposed faces being greater than the internal cohesive forces existing in the slab along the cleavage plane; and maintaining the slab substantially planar as the applied forces overcome the internal cohesive forces along the cleavage plane.
 2. A process according to claim 1 comprising the step of making a trigger cut in an edge of the slab near the cleavage plane.
 3. A process as defined in claim 1 wherein said step of applying a force is carried out by applying a vacuum to each opposed face.
 4. A device for cleaving a slab of rigid laminated material along a cleavage plane of the slab, comprising, in combination: means for supporting the slab in a predetermined orientation; two gripping means each engageable with a major portion of a respective one of the two opposed slab faces parallel to the cleavage plane; and said gripping means being movable away from one another along a common axis perpendicular to the cleavage plane for maintaining the slab in its predetermined orientation while applying uniformly distributed forces to such major portions of the opposed slab faces, which forces are of sufficient amplitude to overcome the internal cohesive forces in the slab along the cleavage plane.
 5. A device as defined in claim 4 further comprising: for each said gripping means; a ram having a barrel secured to said means for supporting and a rod movable relative to said barrel; and connecting means hingedly connecting said gripping means to said rod.
 6. A device according to claim 3 wherein each said gripping means comprises a suction cup connected to a source of vacuum.
 7. A device according to claim 6 wherein each suction cup comprises a plate provided with a peripheral flange housing a flexible sealing joint, and wherein the periphery of the plate substantially corresponds to that of the faces of the slab to be cleaved.
 8. A device according to claim 7 wherein the plate of the cup is provided with abutments arranged to limit the movement of each face of the slab when the vacuum is applied between the suction cup and the slab.
 9. A device according to claim 8 further comprising a sliding cutter operable to form a trigger cut in an edge of the slab to be cleaved.
 10. A process as defined in claim 1 comprising the further step of additionally applying torsional forces to the opposed faces of the slab. 